"Electric power plants are the largest single source of global warming pollution in the country, responsible for nearly 40 percent of greenhouse gas emissions. With sweeping climate legislation effectively dead in Congress, the decision on existing power plants — which a 2007 Supreme Court decision gave to the executive branch — has been among the most closely watched of Mr. Obama's second term.

"The administration has already begun steps to restrict climate-altering emissions from any newly built power plants, but imposing carbon standards on the existing utility fleet would be vastly more costly and contentious."

Bloomberg reports that the plan will include other actions that don't require congressional action, including "pushing energy efficiency standards for appliances [and] clean-energy production on public lands."

According to Bloomberg, the details of the new plan came from energy adviser Heather Zichal, who was speaking Wednesday at a forum sponsored by The New Republic magazine.

Zichal said that Obama "is serious about making it a second-term priority."